Hydraulic jack



Aug- 29, 1950 J. J. MUELLER 2,520,426

HYDRAULIC JACK Filed OC. l5, 1947 Patented Aug. 29, 1950 HYDRAULIC JACKJoseph J. Mueller, St. Joseph, Mich., assignor to Auto SpecialtiesManufacturing Company, St. Joseph, Mich., a corporation of MichiganApplication October 15, 1947, Serial No. 779,845

9 Claims.

This invention relates to hydraulic jacks or pushing and pulling devicesgenerally, wherein an hydraulic cylinder is utilized to contain a ramand wherein the liquid under pressure is pumped into the cylinder to.force the ram outwardly to exert a pushing or lifting action.

Among the objects of the present invention is to provide a constructionof the foregoing nature wherein a very simple means is provided inassociation with the ram, which is the piston operating within thehydraulic cylinder, wherein upon the outermost portion of the lifting orpushing stroke of the ram-like piston, a by-pass will be mechanicallyoperated to permit the liquid under pressure within the ram cylinder topass around the piston into the reservoir whereby to remove the pressurewithin the ram cylinder so that the ram piston cannot travel beyond apredetermined lifting or pushing distance, and wherein if the pumping iscontinued after such a distance has been travelled by the ram piston theliquid will be by-passed so as to prevent breakage.

Another object of the invention resides in providing a constructionwherein a ram piston head is constructed and arranged to cooperate withthe internal walls of the ram cylinder so that as the ram is beingpushed along its lifting or pushing path of travel by the pressure ofthe liquid in the hydraulic cylinder, a leak-proof connection is formedbetween the piston parts, the piston, and the internal Walls of the ramcylinder, and however when the ram piston reaches a predeterminedposition at the end of its travel itautomatically encounters astationary member which, contacting a part of the piston, shifts thepiston with relation to the piston stem or ram, whereby to form aby-pass for the liquid in the ram cylinder to pass the liquid back tothe reservoir and thus relieve any further pressure. I

Yet another object of the present invention resides in providing thelower portion of the ramlike piston with more or less loosely formed andrelatively shiftable parts which are capable of shifting with respect tothe stem or ram of the piston and are arranged so that under pressure ofthe hydraulic liquid in the cylinder for raising or pushing the ram, atight connection is effected which maintains the pressure in the ramcylinder and yet when the ram reaches its outermost stroke therelatively shiftable parts of the piston will contact an abutment,thereby shifting the parts and causing a by-pass passageway to be formedbetween said parts and the ram or piston stem to permit the liquid inthe ram cylinder to by-pass therethrough into the reservoir.

Yet another object of the invention resides in providing a ram having alower portion formed with stepped cylindrical portions upon whichloosely t a three-part piston for the ram head comprising a metallicring, a packing disk, and an outermost ring of relatively hardnon-metallic material which clamps the packing ring between the tworelatively harder rings and wherein these three elements make a loosefit with respect to the stepped portions of the ram itself and inassociation with the ram form a by-pass so that when the ram pistonreaches the uppermost portion of its travel it will contact an abutmentwhereby to shift these relatively loosely fitting annular members withrespect to the ram itself to form a by-pass passage to permit the liquidunder pressure in the ram cylinder to pass the piston and escape to thereservoir whereby to relieve the pressure.

Another object of the invention is to provide a pressure relief devicefor an hydraulic jack wherein the relief device is formed by slidablymounting the ram piston on the ram in a manner to provide a rather looset between the inner walls of the piston and the external walls of thatportion of the ram on which the piston is mounted, the loose fit forminga liquid relief passage which is normally closed on the working strokeof the ram by intercontacting surfaces between the inner walls of thepiston and the external walls of the ram embraced by the piston, and inproviding means at the outer portion of the working stroke of the pistonfor shifting the piston relatively to the ram so as to cause said reliefpassage to open and permit the liquid to pass from the Working sideofthe ram to the relief side of the ram, and which relief side of the ramis always in communication with the reservoir.

Yet another object of the invention resides in providing a pressurerelief mechanism for an hydraulic jack which eliminates cup washerscoring in devices which relieves the ram cylinder of excessive pressureat the outermost working stroke of the ram in the ram cylinder, and thisis accomplished by providing a ram piston which is shiftable bodilyrelatively to the ram and automatically provides a liquid relief passagebetween the connection of the piston and the ram.

These and other objects of the invention will be apparent from a perusalof the following specication lwhen taken in connection with theaccompanying drawing, wherein:

Figure 1 is a sectional view of one type of jack to which the inventionis applied;

Figure 2 is an enlarged view of a portion of Figure 1, taken on the line2--12 of Figure 1, showing the ram moving upwardly with the piston ramparts arranged to hold the pressure within the ram cylinder;

Figure 3 is a section following Figure 2 but showing the ram piston atthe upper end of its travel with the piston parts shifted to provide aliquid passage therethrough to the reservoir; and

Figure 4 is a section taken on the line 4-4 of Figure 2.

Referring now to the drawing in detail, it will be understood that theexemplification of the invention herein is disclosed and illustrated asapplying to any type of hydraulic pushing and pulling device involving aram cylinder and a ram operated hydraulically, and wherein the ram moveswithin the cylinder over a predetermined length of travel and whereinmeans is provided at the en-d of the travel for effecting relief of thepressure in the ram cylinder, through the ram y reservoir I therewithin;The base 2 is threaded about the well 4 as at I2 to receive the lowerthreaded walls of a ram cylinder I4. Also, the base is provided with thedownwardly extending passage I6 and the diagonally disposed counterboreI8. The passage I6 is closed by the plug and the usual type of highpressure pump cylinder 22 is disposed in the bore I8. Within the pumpcylinder 22 lthere operates a piston 24 operated by means of an actuator26 pivoted to the side wall 8 as at 28.

Any type of release valve, not herein shown, may be utilized forrelieving the pressure from the ram cylinder 4 into the reservoir I0. Inaddition to thelpassageway I6 I likewise provide another passageway 30whichconnects a port in the side wall of the pump cylinder I8 with thereservoir I0. It is to be understood that in accordance with the usualcustom an additional reservoir, not shown, and a controlling, manuallyactuated valve for the same, is provided in the base for connecting theram cylinder 4 with the reservoir II) in a manner independently of thepassageways 30 and I6. It is'also to be understood that the bottom ofthe pump cylinder I8 connects as by means of an additional passageway 32with the passage I6 connecting with the ram lcylinder 4.

The outer ends of the cylinders 8 and I4 are closed by means of a, head36 having downwardly extending portion 38 suitably threaded as at 39 toengage the outer threads of the ram cylinder I4, and this ring-like head36 is provided with a shouldered portion 4u which engages the outer endsof the cylinder 8 and clamps tightly thereagainst when the threads 39are drawn up tightly. In addition, the head'36 is provided with aninwardly extending ange 42 through which a ram piston or stem 44 passes.A packing 46 held in position by an externally threaded ring '48 holdsthe packing in place about the ram stem 44. It is noted that thediameter of the ram stem 44 is considerably less than the internaldiameter of the ram cylinder I4. At the upper end of the ram cylinder achamber 50 is provided, and this chamber communicates by means of anelongated passage 52 which terminates as at 53 in open communicationwith the reservoir I0 so that there is a constantly open passage at theupper end of the ram cylinder via the chamber 50, the passage 52, andthe port 53.

The stem 44 is formed on its lowermost end with an internal bore 54which is of considerable 5 diameter and is likewise formed with a, rstannular wall 56 of smaller diameter than the outer diameter of the stem44, thereby forming a shoulder 58. In addition, below the wall 56 whichruns parallel with the outer cylindrical wall 60 of the ram 44, thelower portion of the ram is provided with a parallel wall such as 62which is of even smaller diameter than the wall portion 56, therebycreating a second shoulder 64 which is disposed below the shoulder 58.The lower end of the ram 44 is rolled over to provide a, retainingshoulder 66 which serves to retain or hold the piston proper thereon. Inaddition, the lower end of the ram, just above the shoulder 66, isprovided with a port 68, as seen best in Figures 2 and 3. The piston ispreferably formed of three parts, a metallic ring 10, and a hard rubberring or ring of other relatively hard material 12, which has an annularcutout on its under side of substantially V-shaped form, as shown at 14.The inner wall of this ring ares inwardly as at 16 so that at its topportion of the ring 12 is of lesser cross section than at its bottom,and this taper is so arranged in magnitude that when in the positionshown in AFigure 3 there is a passageway 18 formed between the innerwall of this washer 12 and the o-uter reduced wall 62 of the lowerportion of the ram stem. The lower portion of the relatively hardannulus 12, as shown in Figure 3, is adapted to contact and abut therolled over flange 66 of the ram stem 44.

Disposed between the two relatively hard annuli 10 and 12 is arelatively soft packing 80 which may be of any semi-resilient oryieldable material which will not deteriorate and will hold its form. Itmay be of leather or any usual or desirable material. The inner wall ofthis ring is of substantially the same diameter as the upper portion ofthe inner wall 16 of the lower annulus 12 so that it forms acontinuation of the passage 18 hereinbeforey described.

The combined dimension from top to bottom of the upper annulus 10, thewasher 80, and the lower annulus 12, is less than the distance betweenthe shoulder 58 and the top edge of the rolled abutment or flange 66, sothat the three annuli 10, 80 and 16 may have a shifting movement betweenthe shoulder 58 and the shoulder 66. It is to be noted that the upperwall 82 of the annulus 10 projects beyond the outer wall ,55 of the ram44 but lies within the projection of the flanges 42 on the head 36 sothat when the ram 44 has moved upwardly to the position shown in Figure3, the upper surface 82 of the annulus 1D will strike the lower surfaceof the 60 portion 42 of the head 36 so that on still further outwardmovement of the ram the annulus 10,

the packing 80 and the lower annulus 12 will be shifted downwardly tothe position shown in Figure 3v thereby permitting liquid to flow fromthe ram cylinder 4 from a 4continuation of the well through the port 68,thence via the passage 18, this passage being formed between the innerwall of the annulus 12, the inner wall of the packing and the inner wall-of the upper anmoving upwardly under the pressure within the ramcylinder, the pressure in the ram cylinder will `force the annuli 10, 80and I2 upwardly against the shoulder 58 and likewise against theshoulder 64, thereby blocking off the liquid passage 'I8 to prevent theescape of the liquid to the chamber above the piston so that the pistonin this position will remain a liquid seal not only with the ram stem 44but also with the internal walls of the ram cylinder I4 and it is onlywhen the upward travel has been reached that the upper annulus 'l0strikes the shoulder 42 and the annuli are shifted downward to form afluid connection with the chamber 50 and channel 52 to cause liquid topass therethrough to the reservoir I0, thereby relieving furtherpressure in the raml cylinder and preventing breakage in the parts.v Itwill be noted from the foregoing that by,

reason of this loose connection or loose flt between the annuli on thelower end of the ramA stem, the formation of the port therein andthedisposition of the upper channel 50, the passage- 52, and the port 53back to the reservoir, I have' provided a very simple, inexpensive meansfor relieving the pressure in the ram cylinder at the outermost portionof the lifting or pushing stroke,

and which construction at the same time provides -a liquid seal of thepiston against the ram stfnf'i and the inner walls of the ram cylinder.By means of this construction I eliminate the heretofore present scoringof the walls of relief valves by the passage of liquid therethroughunder the heavy pressure of the liquid in the ram cylinder as itby-passes the ram and is passed into the reservoir. Underthe presentconstruction I have eliminated the necessity of expensive shiftablevalves, ball valves, springs, and other constructions which generallyinclude a scoring of the valve parts under the terrific strain of theliquid in the ram cylinder escaping, and provide a simple type ofmechanism for relieving pumping pressure when the ram has reached itsoutermost position. By means of the construction I have provided a loosefit between the ram piston and the ram stem by means of the shoulderedconstruction of the ram stem on its lower end and have utilized theloose t to provide shiftable parts of the piston providing a liquidpassageway to pass the escaping liquid from the ram cylindertherethrough at the proper time and in aA manner to prevent the scoringofi. .f

the walls which would otherwise tend to increase the size of the passageand ultimately prevent correct passage, while at the same time there hasbeen assured a complete sealing of the liquid under proper workingconditions.

It is apparent that many widely Vdifferent embodiments of this inventionmay be made without departing from the spirit and scope thereof, andtherefore it is not intended to be limited except as indicated in theappended claims.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

l. In combination, a base, a ram cylinder formed on the base and areservoir associated with the base and the ram cylinder, a ram operablein the cylinder and having a portion of smaller diameter than thecylinder, pump means for drawing liquid from the reservoir and forforcing liquid into the ram cylinder, the lower portion of the ram beingof reduced diameter and a piston shiftably mounted on said portion ofthe ram reduced diameter, said piston being of an external diametersnugly fitting the interior wall of the ram cylinder, means includingthe internal walls of said piston in association with the externalreduced surface of the ram providing a pressure release passageconnecting portions of the ram cylinder on opposite sides of the piston,and means disposed in the path of travel of the piston as it approachesits extreme limit of outward travel for shifting the piston on the ramto open said release passage to allow the liquid in one end of thecylinder to flow therethrough to the opposite end of the cylinder, and anormally open passageway connecting the opposite side of the ramcylinder with the reservoir.

2. An hydraulic jack comprising a base having a ram cylinder and areservoir, a ram in the ram cylinder, said ram being of less diameterthan the ram cylinder, said ram having its lower end formed of decreaseddiameter, a piston mounted on said ram portion of decreased diameter andcapable of shifting movement therealong in the direction of thelongitudinal axis of the ram, the external wall of said piston forming aliquid-tight t with the inner wall of the ram cylinder, and meansassociated with the internal walls of the ram piston and the outer wallof the ram stem along Whichthe ram piston ismovable forming a liquidby-pass passage through the ram piston, means at the upper end of theram cylinder forming an unobstructed liquid passage therefrom to thereservoir, said piston when subjected to the pressure of the ramcylinder in the raising of the load forming a liquid seal with the wallsof the ram stem which are of reduced diameter, and said piston havingmeans thereon causing the same to be shifted longitudinally of the ramstem when said piston reaches the outermost portion of its workingstroke whereby the piston is shifted longitudinally of the ram stem toform a passageway between the inner walls of the piston and the reducedportion of the ram stem which it surrounds to permit the liquid to passtherethrough and into the reservoir.

3. An hydraulic jack comprising a base, a ram cylinder thereon and areservoir thereon, means for creating hydraulic pressure in the ramcylinder, a ram in the ram cylinder, said ram including a pistonoperable by the pressure in the ram cylinder to raise the ram, said rambeing of lesser diameter than the internal walls of the ram cylinder,the lower portion of the ram being of reduced diameter and providingshoulders thereon, a piston mounted on said portion of reduced diameterof the ram, the internal walls of the piston being of lesser diameterthan the external walls of the reduced diameter of the ram whereby toprovide a liquid by-pass between the internal walls of the piston andthe external walls of reduced diameter of the ram, said piston beingshiftable along the ram portion of reduced diameter in a directionlongitudinally of the longitudinal axis of the ram, and said piston andportion of reduced diameter of the ram and said shoulders formed in saidportion of reduced diameter being operable under the pressure in the ramcylinder to shift said piston against said shoulders to close saidby-pass passageway to prevent passage of liquid therethrough, and meansdisposed at the outer end of the ram cylinder adapted to contact saidpiston to shift it longitudinally of the ram portion of reduced diameterto open said by-pass passageway to permit the passage of liquidtherethrough to relieve the pressure in the ram cylinder.

4. An hydraulic jack comprising a base, a ram cylinder thereon and areservoir, a ram in the ram cylinder of less diameter than the internalwalls of the ram cylinder, the lower end of the ram having a wall ofreduced diameter to provide an upper shoulder disposed normally to thelongitudinal axis of the ram and having a second portion of greaterreduced diameter than the first mentioned portion to provide anintervening shoulder extending normally to the longitudinal axis of theram, the outer end of the lower portion of the ram being provided with aretaining shoulder and an annular piston disposed about that portion ofthe ram of reduced diameter between the upper shoulder and the retainingshoulder, the length of the piston between said shoulders being lessthan the distance apart of said shoulders, the internal walls of saidpiston being of greater diameter than the external walls of the portionof reduced diameter of the ram whereby to provide a liquid by-passpassage through the piston, means at the upper end of the ram cylinderforming a liquid passage therefrom to the reservoir, and means disposedin the path of travel of the ram piston as it reaches its outermostlimit of travel along the ram cylinder adapted to contact said piston toshift the same relatively to the ram on which it is mounted for openingsaid by-pass passage to permit liquid under pressure in the ram cylinderto pass to the end of the ram cylinder and through said liquid passageand into the reservoir.

5. A device as set forth in claim 4 wherein the piston is composed ofthree parts, an upper metallic annulus, a lower annulus of hardmaterial, and an intermediate packing annulus or washer, the uppersurface of the metallic annulus being adapted to contact the rstshoulder and the upper surface of the packing annulus being adapted tocontact the second shoulder, and the lower inner wall of the thirdannulus being adapted to contact the retaining shoulder in the alternatemovements of the piston relatively to the ram, and the outer walls of atleast one of said annuli making a liquid-tight seal with the inner wallsof the ram cylinder.

6. In combination, a base, a ram cylinder and a reservoir, a ram in theram cylinder, said ram having a reduced diameter compared with the,diameter of the internal walls of the ram cylinder, a piston on thelower end of the ram, the outer walls of the piston making aliquid-tight seal with the internal walls of the ram cylinder, theinternal walls of the piston and the external walls of the lower part ofthe ram being formed to provide a loose fit therebetween to provide a,liquid by-pass passage therebetween, said piston being shiftable alongthe lower end of the ram in a direction parallel to the longitudinalaxis of the ram, and said lower portion of the ram providing shoulderedmeans in one position to engage the piston to form a liquid-tight sealtherewith to close the liquid passage between the inner walls of thepiston and the reduced portion of the ram, means forming a liquidconnection between the upper end of the cylinder and the reservoir,means disposed in the path of travel of the piston at the outer portionof the path of travel of the ram in the ram cylinder for contacting thepiston to shift it longitudinally whereby to open the passage formedbetween the internal walls of the piston and the external walls of thelower portion of the ram to permit liquid under pressure in the ramcylinder to pass therethrough and escape to said passages and into thereservoir.

7. In an hydraulic device, the combination of a ram cylinder and a ramshiftable therealong under liquid pressure in the ram cylinder, the ramhaving a piston shiftably mounted thereon and forming a loose fittherewith toprovide in one position a liquid by-passage between the ramand the piston and in another position and under the pressure of theliquid in the ram cylinder to press the piston against a portion of theram to block said passage, and means disposed at the outermost path oftravel of the ram in the ram cylinder for shifting the piston relativelyto the ram to open said passage to permit the passage of liquid throughthe piston.

8. An hydraulic jack comprising a base and a ram cylinder, a ram in thecylinder of less diameter than the internal diameter of the cylinder, apiston slidably mounted on said ram and having external walls snuglyfitting the cylinder, the internal Walls of the piston being of largerdiameter than that portion of the external walls of the ram which aresurrounded by the piston to form a liquid relief passage, and saidexternal walls of the ram having portions engageable by said piston toclose said passage, said piston when subjected to working pressure inthe ram cylinder being shiftable to a position along said ram so as toclose said relief passage, and means operated by said movement of thepiston as it arrives substantially at the end of the working stroke ofthe ram for shifting the piston along the ram for opening the reliefpassage between the internal walls of the piston and the walls of theram embraced thereby.

9. In combination with a, ram cylinder, a ram in the cylinder, liquidsealing means disposed on the ram and slidably and continuously engagingthe inner wall of the ram cylinder and forming a liquid-tight seal withthe inner wall of the cylinder, said sealing means being shiitablymounted on said ram and under pressure created by the pressure in oneend of the ram cylinder being operable for sealing against said ram,said sealing means cooperating with said ram to form a liquid passageoperable when said passage is not sealed to pass liquid under pressurethrough said passage only when the ram approaches one end of thecylinder, and means operableI in the path of said sealing means as saidram approaches its extreme movement in one direction with respect to thecylinder and operable on said sealing means for shifting said sealingmeans relatively to the ram to open said liquid passage for relievingthe pressure in said working pressure end of said cylinder.

JOSEPH J. MUELLER.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,707,497 Shevlin Apr. 2, 19292,136,835 Begg NOV. 15, 1938 2,322,314 Pomeroy June 22, 1943 2,352,920Stevens July 4, 1944 2,438,317 Gabriel Mar. 23, 1948

